Externally valved shunts for a cardiopulmonary bypass pump are disclosed in U.S. Pat. No. 4,553,532 dated Nov. 19, 1985 and U.S. Pat. No. 5,383,839 dated Jan. 24, 1995, wherein roller-like valve elements and external plate valves are positioned at the inlet and outlet of a compressible tubing shunt for controlling the flow of blood through the tubing mounted in the compression chamber of a pulsatile flow pump.
While the roller-like valve elements and external plate valves have performed their intended function, the slot valve of the present invention is an improvement thereon in that the slot valve of the present invention provides a larger orifice for the blood to flow through, thereby diminishing the work of the pump, and reducing the velocity of the blood flow through the outlet slot valve, thus, lessening the shear stress upon the red blood cells and other particulate matter, such as the large molecules, albumin, and globulin, whereby trauma to the blood is reduced.